This invention relates to a crawler vehicle of the kind that comprises a main frame carried by two parallel crawler assemblies with frames that are mounted to the main frame to be pivotable relative to each other about axes transverse to the crawler frames.
In prior art vehicles of this kind, very high and troublesome dynamic stresses will appear both in the main frame and in the crawler frames when the vehicle moves in rough terrain due to the crawler frames being pivotably mounted to the main frame in conventional slide bearings that only permit movements in one plane. Particularly, very high bending loads will appear as a result of "toeing in" of the crawler frames. As a result of these high stresses, the main frame as well as the crawler frames must be overdimensioned and unnecessarily heavy.
Another problem associated with prior art vehicles of this kind is the demand for frequent maintenance in the form of lubrication of the bearings. In spite of a time consuming maintenance, the life of the conventional bearings is limited and the bearings cause considerable standstill and costs for renovation.
The present invention is intended to solve the problems and provided for a crawler vehicle in which the bending stresses in the main frame and the crawler frames and between the frames are considerably reduced. The invention also makes possible a lighter and cheaper construction of the frames of the vehicle.
According to the invention, elastic elements are utilized in the bearings between the crawler frames and the main frame.
In prior art vehicles of the kind referred to in which a transverse beam is connected between the crawler frames to support the main frame and balance the pivotal movement of the crawler frames, a cheaper and more robust construction can be provided by the present invention at the same time as the dynamic loads on the construction and the demands for maintenance are considerably reduced. In order to make possible any pivoting of the crawler frames, prior art vehicles of this kind have connections between the transverse beam and the crawler frames that permit free movement transverse to the crawler frames. Alternatively, the transverse beam has been constructed to permit free variation of its length during the pivoting of the crawler frames. Such arrangements mean that the transverse beam cannot transmit laterally directed forces from the crawler frames to the main frame and, as a result, all lateral forces and bending forces must be taken up in the bearings that directly connect the crawler frames to the main frame. In turn, this fact results in that very high bending forces will be imposed on the bearings, and the bearings and the crawler frames must be dimensioned to withstand these forces.